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What Does L-Theanine Do in Pre-workout? Learn From Experts 

Anthony Diaz
Published by Anthony Diaz | Bodybuilding Coach
Last updated: August 9, 2023
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The advice I give my fitness clients when it comes to choosing a pre-workout supplement is to read the label and stay away from proprietary blends.

This advice paves the way for a plethora of questions about individual ingredients.

One of those ingredients is l-theanine.

I dove into extensive research on this common pre-workout ingredient and compiled a little mini-guide, so you know what l-theanine is and what it does.

Let’s unpack it now.

Quick Summary

  • L-theanine in pre-workouts helps improve focus, and balance when working out.
  • Green tea, black tea, and some mushrooms are some products you can extract L-theanine, an amino acid.
  • L-theanine also promotes weight loss, promotes relaxation, reduces blood pressure, boosts the immune system, improve sleep quality, and increase cognitive functions.

L-Theanine in Pre-workout: All You Need to Know

Scooping a supplement powder from the container

Research shows that l-theanine increases focus and balances stimulant effects, making it an increasingly popular addition to pre-workout supplements [1].

Let’s take a closer look.

What Is L-Theanine?

L-theanine is an amino acid found in black and green tea and some mushroom varieties. It has similar traits to glutamine, a naturally occurring amino acid; however, it sometimes seems to block glutamine’s effects [2].

Glutamine is a necessary amino acid to build protein and aid the creation of other amino acids and glucose [3].

The human body does not produce l-theanine, and it is not necessary for any of its functions.

L-theanine is not to be confused with threonine, another amino acid that acts differently.

How Does L-Theanine Work?

L-theanine works by affecting certain brain chemicals like serotonin and dopamine. These chemicals affect physiological stress responses, mood, emotions, and sleep quality [4].

L-theanine supplementation may:

  • Improve sleep quality.
  • Promote relaxation.
  • Increase cognitive performance.
  • Promote weight loss.
  • Boost the immune system.
  • Reduce blood pressure.

So how does one amino acid play a role in all that?

L-theanine increases gamma-aminobutyric acid( GABA) levels and other brain-calming chemicals while at the same time decreasing chemicals linked to stress and anxiety. 

L-theanine also enhances alpha brain wave activity, which is responsible for that mental feeling you experience while meditating, daydreaming, or being creative [5].

Essentially l-theanine can reduce anxiety symptoms and make you feel calm without sedating you.

L-Theanine and Caffeine for Maximum Benefits

Top view of powdered supplement

L-theanine works synergistically with caffeine to offer an energy boost, improved mental health, and brain power.

Caffeine may improve attention span, the ability to process visual information, and accuracy when switching between tasks.

When paired with caffeine, l-theanine may further improve focus and attention.

A placebo-controlled study evaluating supplementation with both l-theanine and caffeine shows that when working in tandem, these two substances enhance the speed and accuracy of cognitively demanding tasks [6].

Another study shows supplementation of l-theanine with caffeine and tyrosine (a non-essential amino acid) enhanced performance in athletes where their sport required rapid and precise movement [7].

When working with clients who complain about the lack of focus after a hard day at work, I usually recommend pre-workouts that contain a combination of these ingredients.

The results start to show almost immediately.

“L-theanine may reduce brain fog symptoms such as memory problems and delayed reaction time when taken as a supplement. It may also help reduce stress and improve sleep, which may relieve brain fog symptoms.”

- Lisa Hodgson, Clinical Nutrition Manager at Saratoga Hospital

L-Theanine as a Nootropic

Pointing at head

Nootropics, also known as “smart drugs” or “cognitive enhancers,” improve cognitive function by increasing attention, creativity,  memory, and motivation [8].

L-theanine is one of the nootropics that work because easily passes through the blood-brain barrier, which controls what substances enter and leave the brain.

This barrier is a network of blood vessels and tissues that help keep harmful substances out of the brain [9].

Green tea is the most common source of l-theanine, with approximately 25 mg in each cup, and pre-workout and other supplements can contain as much as 500 mg.

The nootropic benefits of l-theanine in green tea or as an ingredient in pre-workout may benefit you on non-workout days by aiding cognitive function for studying or getting through the work day.


Can You Get Addicted To L-Theanine?

You are unlikely to get addicted to l-theanine. Addiction occurs when a substance releases high dopamine levels, resulting in a need to seek out the “reward” feeling. L-theanine releases relatively low dopamine levels, lowering the risk of addiction.

Does L-Theanine Show Up On A Drug Test?

L-theanine should not show up on a drug test as it is a naturally occurring substance, an amino acid found in black and green tea and some mushrooms.

Is L-Theanine Good in a Pre-workout?

I tell my clients that fitness success encompasses the whole body, physically and mentally, including the ever-important brain health.

There is no doubt in my mind that l-theanine helps brain function and is an incredibly valuable ingredient in pre-workout.

Our team tried and tested dozens of pre-workouts until we finally compiled the list of the best pre-workouts for focus and contain l-theanine.

These products can enhance your gym sessions and reduce mental stress, which plays a significant role in helping you meet your fitness goals.

When your brain is healthy, your energy levels increase, and you are more motivated to work out.


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